1. Field of the Invention
The present invention relates to a heating apparatus for a vehicle. The heating apparatus is suitable for a vehicle having a diesel engine or a lean burn engine, for example.
2. Description of Related Art
In a conventional heating apparatus for a vehicle, a passenger compartment is heated using cooling water for cooling an engine of the vehicle as a heating source. However, in a vehicle having a diesel engine or a lean burn engine, the passenger compartment cannot be sufficiently heated by cooling water of the engine.
To overcome this problem, in a heating apparatus disclosed in JP-U-63-50713, a pump is operatively linked with a vehicle wheel, a throttle member is disposed at a fluid-discharge portion of the pump in a loop-like fluid passage, and throttle state of the throttle member is switched by a manually operated lever. In the heating apparatus, because the lever for changing the throttle state of the throttle member is manually operated, the lever operation is troublesome and is difficult to be accurately controlled. Further, because an opening degree of the throttle member is decreased so that the temperature of fluid is increased, an amount of fluid flowing through the throttle member is decreased, thereby decreasing heating capacity of the heating apparatus.